The present disclosure relates to semiconductor processing methods, and particularly to methods for low damage etch process for low dielectric constant materials, and structures for effecting the same.
In a dense contact via hole array, the pitch of the contact via holes is limited by lithographic resolution. The smaller the distance between a pair of contact via holes is, the greater the probability that a physical pattern is bridged, either at a lithographic step or after a pattern transfer etch. While multi-mask patterning schemes that employ multiple lithographic masks can alleviate bridging of contact via holes as printed in each developed photoresist layer, an adjacent pair of contact via holes is prone to bridging upon transfer of multiple lithographic patterns in the photoresist layers into an underlying layer. Thus, via hole bridging poses a severe limitation in scaling of dimensions in a dense contact via hole array.